rhiza. This species has dise-like fronds 
or thalli that may reach a diameter of 
eight millimeters and has several root- 
letse se hese. Inttle 
apologies for roots, 
“Duckmeats” with 
perpetuating their 
species by branching and separation from 
the parent, seem far from the accepted 
idea of a flowering plant, but neverthe- 
less the extremely tiny Wolffia Columbi- 
ana is the last word in this direction. The 
plant consists of a minute green globule 
about one millimeter in diameter, floating 
just below the surface of the water. It is 
considered rare, but that may be due to 
its size and the proneness of the unfa- 
miliar to think it a tiny green seed. The 
Duckweeds 
plants known to botanists. 
are the smallest flowering 
The great abundance of some of the 
the 
aquarist to exercise any concern about 
species render it unnecessary for 
“wintering” his plants, but, without much 
trouble, a few can be carried over to se- 
cure a start in advance of Nature out- 
doors. Of course, if one secures the rarer 
or more attractive trisulca, he may well go 
to some trouble. Microscopic life is, of 
course, present on the rootlets and under 
side of the fronds. 
the fish, which may be seen to take a plant 
This is well known to 
in their mouths and, in a moment or so, 
disgorge it. 
(To BE ConciupED) 
Note on Hearing of Fishes 
J. T. Nicos 
New York 
Dr. G. H. Parker, of Harvard Univer- 
sity, has been experimenting with the 
He finds that sounds in 
the air usually cannot be heard well under 
hearing of fishes. 
water, and that sounds under water usually 
cannot be heard well in the air. Many 
fishes show certain proof of distinctly hear- 
ing under water sounds. 
Dr. Parker’s article is Doc. No. 755, 
Bureau of Fisheries, Wash., “Sound as a 
Directing Influence in the Movements of 
Fishes.” 
21 
A Surgical Case 
W. F. DeVore 
Brooklyn 
On a certain occasion I happened to stop 
in the store of one of our local fish dealers, 
and in looking over his stock, saw a gold- 
fish swimming about with its head down. 
At the first glance, I thought the fish was 
affected with bladder trouble, as this is 
one of the symptoms of that disease. Upon 
closer examination, however, I found that 
there was a sack projecting from the lower 
part of the jaw, and out of curiosity I 
The 
sack felt hard to the touch and I was in- 
removed the fish and examined it. 
clined to believe that it was due to an 
abnormal growth. However, as a further 
experiment, I took a pen-knife from my 
pocket and proceeded to open the sack, 
and to my great surprise, there dropped 
out several pieces of gravel, some fully 
one-eighth inch in diameter. On placing 
the fish in the tank, it almost immediately 
righted itself and swam about in a nor- 
mal manner. Upon inquiring at the store 
a week later, I found the fish apparently in 
good health and no trace of its former dis- 
ability. 
was held downward by the weight of the 
It seems conclusive that this fish 
gravel, but the mystery was how did the 
gravel happen to lodge in the fish’s mouth 
in such a manner, particularly, as it was 
We all 
know the propensity of goldfish to suck 
entirely covered with the growth. 
gravel into the mouth, but they usually 
eject the same immediately after doing so. 
According to habitat, fishes fall into two 
main groups, marine and freshwater, with 
an intermediary group inhabiting the trans- 
The last 
group can live either in salt or fresh water 
or become adapted to either, or 
ition region of brackish water. 
some 
species may be strictly confined to areas of 
certain degrees of density or sal nity. 
